The present invention generally relates to fuel fired heating apparatus and, in a representatively illustrated embodiment thereof, more particularly provides a fuel-fired water heater having incorporated therein a specially designed raw fuel jet pilot structure and associated burner clogging detection apparatus.
Despite continuing improvements in the fuel efficiency of and reduction in undesirable operating emissions therefrom, modern fuel-fired water heaters still have various operational characteristics which are less than entirely satisfactory. For example, the burner pilots in most if not all conventional fuel-fired water heaters draw their combustion air from the area within the combustion chamber surrounding the pilot burner and its associated main burner. In some water heater combustion chamber configurations this air surrounding the pilot is diluted with exhaust gases. This undesirably reduces the amount of available oxygen for proper pilot combustion. With respect to this pilot-related problem, the water heater designer is faced with two conflicting design criteria— the need for the pilot to be close to the main burner for proper ignition thereof, and the need for the pilot to be near a clean combustion air source for proper pilot combustion.
Another design challenge associated with modern fuel-fired water heaters is that they typically operate in locations that are not regularly cleaned (for example, in attics, closets, basements, sheds, etc.). Due to the presence of various types of contaminants present in such locations, which tend to clog various components of the water heater such as its burner, the water heater must either be able to operate reliably and safely throughout its life, or, in the case of extreme contamination from clogging materials such as lint, dust and oil, needs to be designed to safely shut itself down before producing undesirably high levels of carbon monoxide caused by clogging of various components of the water heater.
As can be seen from the foregoing, a need exists for a fuel-fired water heater having improvements in the above-described areas. It is to this need that the present invention is primarily directed.